Strategy Pattern

strategy_pattern.rb

class TextParser
  attr_reader :text, :parser

  def initialize(text, parser)
    @text   = text
    @parser = parser
  end

  def call
    parser.call(text)
  end
end

class XMLParser
  def call(text)
    "<text>#{text}</text>"
  end
end

class JSONParser
  def call(text)
    "{ text: #{text} }"
  end
end

puts TextParser.new('My Text', XMLParser.new).call
puts TextParser.new('My Text', JSONParser.new).call

# -> (text) { text.reverse } is a reference to a lambda. This demonstrates 
# the power of functional programming. 
puts TextParser.new('My Text', -> (text) { text.reverse }).call